Biological tissue rootage face, implant, method for forming biological tissue rootage face, and method for producing implant

ABSTRACT

A biological tissue rootage face (30) capable of closely bonding to a biological tissue (H, S) is composed of a biocompatible material and has numerous fingertip-shaped microvilli (41). The microvilli (41) have tip diameters in the order of nanometers. An implant (1) has the biological tissue rootage face (30) on a surface (11, 24) configured to root into a biological tissue (H, S). In a method for forming the biological tissue rootage face (30), a surface of a biocompatible material is subjected to laser nonthermal processing carried out by emitting a laser beam in air, to form numerous fingertip-shaped microvilli (41). The laser beam is a laser beam of an ultrashort pulse laser.

TECHNICAL FIELD

The present invention relates to a biological tissue rootage face, animplant, a method for forming the biological tissue rootage face, and amethod for producing the implant.

BACKGROUND ART

Implants for body implantation have attracted attention. Implantsinclude dental implants, artificial joints, artificial bones, and thelike.

The dental implants are formed of a biocompatible material such as abiocompatible metallic material or a biocompatible ceramic material. Thebiocompatible metallic materials include titanium, a titanium alloy, acobalt-chromium alloy and the like. The biocompatible ceramic materialsinclude alumina, zirconia and the like.

A hip prosthesis, an artificial bone and the like are formed of abiocompatible metallic material and a biocompatible ceramic material, aswell as a biocompatible resin material.

An outer surface of the implant closely bonds to a bone (hard tissue).The outer surface of the implant is roughened (porosification, etc.), sothat bone ingrowth is enhanced, and high osseointegration can beobtained.

A resin implants can be exemplified by an implant prepared by coating aresin surface with a metal or a ceramic and roughening this coating.

FIG. 19 presents images (4 items) of outer surfaces of conventionaltitanium fixtures taken by SEM (magnification: 2,000 times). These outersurfaces are roughened (porosified) by etching treatment withhydrochloric acid or the like, or blasting treatment.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Laid-Open No. 2010-5379

SUMMARY OF INVENTION Problem to be Solved

Even when an outer surface of an implant is roughened, it takes severalweeks to several months for the implant to be osteointegrated. Ifexcessive force is applied to the implant during this period,osseointegration becomes difficult, e.g. the surrounding bones or thelike are damaged, or osseointegration is delayed. Thus, it is necessaryto further improve the osseointegration of the implant (bondability tohard tissues).

Since the implant is closely bonded not only to a bone but also tomucosal tissues (soft tissues) surrounding the bone, the conglutinationproperty (affinity) with the soft tissues is also important. Whenadhesion of the dental implant with a gingiva is insufficient, thegingiva has inflammation, and the gingiva (gum) may be contracted, or analveolar bone may be reduced (bone resorption). For this reason,conglutination property of the dental implant with the gingiva(conglutination property with soft tissues) should be improved toprevent (block) bacterial invasion.

Implants require improvement of the ability of rooting into biologicaltissues (bondability with hard tissues, and conglutination property withsoft tissues) and acceleration of biological tissue fusion.

An object of the present invention is to provide a biological tissuerootage face capable of improving the ability of rooting into biologicaltissues, an implant, a method for forming the biological tissue rootageface, and a method for producing the implant.

Solution to Problem

A first embodiment of a biological tissue rootage face according to thepresent invention is characterized in that the biological tissue rootageface is capable of rooting into a biological tissue, is composed of abiocompatible material and has numerous fingertip-shaped microvilli.

A second embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in the first embodiment,the microvilli have tip diameters in the order of nanometers.

A third embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in the secondembodiment, the tip diameters are 50 nm or more and less than 500 nm.

A fourth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in any one of the firstto third embodiments, a size of a three-dimensional surface roughness Sais in the order of nanometers.

A fifth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in any one of the firstto fourth embodiments, a developed area ratio Sdr of an interface is 0.1or more and 2.0 or less.

A sixth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in any one of the firstto fifth embodiments, the biological tissue rootage face has a pluralityof first grooves having widths of 1 μm or more and 50 μm or less.

A seventh embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in the sixth embodiment,the first grooves have depths of 1 μm or more and 20 μm or less.

An eighth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in the sixth or seventhembodiment, the first grooves are arranged in parallel or in a latticepattern.

A ninth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in any one of the firstto eighth embodiments, the biological tissue rootage face has aplurality of second grooves having widths of 10 μm or more and 500 μm orless.

A tenth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in the ninth embodiment,the second grooves have depths of 5 μm or more and 500 μm or less.

An eleventh embodiment of the biological tissue rootage face accordingto the present invention is characterized in that, in the ninth or tenthembodiment, the second grooves are arranged in parallel or in a latticepattern.

A twelfth embodiment of the biological tissue rootage face according tothe present invention is characterized in that, in any one of the firstto eleventh embodiments, the biocompatible material is a biocompatibleceramic material.

A thirteenth embodiment of the biological tissue rootage face accordingto the present invention is characterized in that, in the twelfthembodiment, the biocompatible ceramic material contains zirconia.

A fourteenth embodiment of the biological tissue rootage face accordingto the present invention is characterized in that, in any one of thefirst to the eleventh embodiments, the biocompatible material is abiocompatible metallic material.

A fifteenth embodiment of the biological tissue rootage face accordingto the present invention is characterized in that, in the fourteenthembodiment, the biocompatible material contains titanium, a titaniumalloy, or a cobalt-chromium alloy.

A sixteenth embodiment of the biological tissue rootage face accordingto the present invention is characterized in that, in any one of thefirst to eleventh embodiments, the biocompatible material is abiocompatible resin material.

A seventeenth embodiment of the biological tissue rootage face accordingto the present invention is characterized in that, in the sixteenthembodiment, the biocompatible resin material contains apolyetheretherketone resin.

A first embodiment of the implant according to the present invention ischaracterized in that the implant is capable of rooting into abiological tissue and has any one of the first to seventeenthembodiments of the biological tissue rootage face according to thepresent invention on a surface configured to root into a biologicaltissue.

A second embodiment of the implant according to the present invention ischaracterized in that, in the first embodiment, the implant is ascrew-type fixture of a dental implant and the biological tissue rootageface is provided on at least one of a screw face, a collar face and atip face.

A third embodiment of the implant according to the present invention ischaracterized in that, in the first embodiment, the implant is acylinder-type fixture of the dental implant and the biological tissuerootage face is provided on at least one of the tip face and an outerperipheral face.

A fourth embodiment of the implant according to the present invention ischaracterized in that, in the first embodiment, the implant is anabutment of the dental implant and the biological tissue rootage face isprovided on a gingival margin face.

A fifth embodiment of the implant according to the present invention ischaracterized in that, in the first embodiment, the implant is a stem ofa hip prosthesis and the biological tissue rootage face is provided on asurface of a site implanted in a femur.

A first embodiment of a method for forming the biological tissue rootageface according to the present invention is characterized in that themethod is a method for forming the biological tissue rootage facecapable of rooting into a biological tissue, wherein a surface of abiocompatible material is subjected to laser nonthermal processingcarried out by emitting a laser beam in air, to form numerousfingertip-shaped microvilli.

A second embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the first embodiment, the laser beam is a laser beam of anultrashort pulse laser.

A third embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the second embodiment, the laser beam is a laser beam of apicosecond laser or a femtosecond laser.

A fourth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in any one of the first to third embodiments, the microvilli havetip diameters in the order of nanometers.

A fifth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in any one of the first to fourth embodiments, a ceramic sinteredcompact composed of a biocompatible ceramic material is non-thermallyprocessed with laser.

A sixth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the fifth embodiment, the biocompatible ceramic materialcontains zirconia.

A seventh embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in any one of the first to fourth embodiments, an acid-etchedmetallic workpiece composed of a biocompatible metallic material isnon-thermally processed with laser.

An eighth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the seventh embodiment, the biocompatible metallic materialcontains titanium, a titanium alloy, or a cobalt-chromium alloy.

A ninth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in any one of the first to fourth embodiments, a resin compactcomposed of a biocompatible resin material is non-thermally processedwith laser.

A tenth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the ninth embodiment, the biocompatible resin material containsa polyetherether ketone resin.

An eleventh embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in any one of the first to tenth embodiments, a plurality of firstgrooves having widths of 1 μm to 50 μm and depths of 1 μm to 20 μm areformed by scanning the surface of the biocompatible material with thelaser beam.

A twelfth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the eleventh embodiment, the first grooves are arranged inparallel or in a lattice pattern by scanning the surface of thebiocompatible material with the laser beam in a parallel direction or anintersecting direction.

A thirteenth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in any one of the first to twelfth embodiments, a plurality ofsecond grooves having widths of 10 μm to 500 μm and depths of 5 μm to500 μm are formed by scanning the surface of the biocompatible materialwith the laser beam.

A fourteenth embodiment of the method for forming the biological tissuerootage face according to the present invention is characterized inthat, in the thirteenth embodiment, the second grooves are arranged inparallel or in a lattice pattern by scanning the surface of thebiocompatible material with the laser beam in a parallel direction or anintersecting direction.

A first embodiment of a method for producing the implant according tothe present invention is characterized in that the method is a methodfor producing the implant capable of rooting into a biological tissue,wherein a step of forming the surface capable of rooting to thebiological tissue includes any embodiments of the first to fourteenthembodiments of the method for forming the biological tissue rootage faceaccording to the present invention.

A second embodiment of the method for producing the implant according tothe present invention is characterized in that, in the first embodiment,the implant is a fixture of a dental implant.

A third embodiment of the method for producing the implant according tothe present invention is characterized in that, in the first embodiment,the implant is an abutment of the dental implant.

A fourth embodiment of the method for producing the implant according tothe present invention is characterized in that, in the first embodiment,the implant is a stem of a hip prosthesis.

Effects of Invention

The biological tissue rootage face, the implant, the method for formingthe biological tissue rootage face, and the method for producing theimplant according to the present invention can improve the ability ofrooting into the biological tissue.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 presents drawings of a dental implant 1 according to the firstembodiment of the present invention, including (a) a screw-type dentalimplant 1A and (b) a cylinder-type dental implant 1B.

FIG. 2 presents images of a biological tissue rootage face 30(biological tissue rootage face 31) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 30 times, (b) an image at a magnification of 200 times,and (c) an image at a magnification of 500 times.

FIG. 3 presents images of the biological tissue rootage face 30(biological tissue rootage face 31) according to the first embodiment ofthe present invention taken by SEM, including (d) an image at amagnification of 2,000 times, (e) an image at a magnification of 5,000times, and (f) an image at a magnification of 10,000 times.

FIG. 4 presents images of the biological tissue rootage face 30(biological tissue rootage face 32) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, and (c) an image at a magnification of 2,000 times.

FIG. 5 presents images of the biological tissue rootage face 30(biological tissue rootage face 32) according to the first embodiment ofthe present invention taken by SEM, including (d) an image at amagnification of 5,000 times, (e) an image at a magnification of 10,000times, and (f) an image at a magnification of 20,000 times.

FIG. 6 presents referential images of a small intestinal surface takenby SEM, including (a) an image at a magnification of about 100 times,(b) an image at a magnification of about 5,000 times, and (c) an imageat a magnification of about 10,000 times.

FIG. 7 presents images of a biological tissue rootage face 30(biological tissue rootage face 33) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 2,000times, (c) an image at a magnification of 5,000 times, and (d) an imageat a magnification of 10,000 times.

FIG. 8 presents images of abiological tissue rootage face 30 (biologicaltissue rootage face 34) according to the first embodiment of the presentinvention taken by SEM, including (a) an image at a magnification of 200times, (b) an image at a magnification of 500 times, and (c) an image ata magnification of 10,000 times.

FIG. 9 presents images of a biological tissue rootage face 30(biological tissue rootage face 35) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 500 times, and (b) an image at a magnification of10,000 times.

FIG. 10 presents drawings of a dental implant 3 according to the secondembodiment of the present invention, including (a) screw-type dentalimplant 3A and (b) cylinder-type dental implant 3B.

FIG. 11 presents images of a biological tissue rootage face 70(biological tissue rootage face 71) according to the second embodimentof the present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, and (c) an image at a magnification of 2,000 times.

FIG. 12 presents images of a biological tissue rootage face 70(biological tissue rootage face 71) according to the second embodimentof the present invention taken by SEM, including (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

FIG. 13 presents images of an outer surface 51 of an acid-etchedtitanium workpiece taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, and (c) an image at a magnification of 2,000 times.

FIG. 14 presents images of the outer surface 51 of the acid-etchedtitanium workpiece taken by SEM, including (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

FIG. 15 presents a drawing of a hip prosthesis 101 according to thethird embodiment of the present invention.

FIG. 16 presents images of a biological tissue rootage face 130(biological tissue rootage face 131) according to the third embodimentof the present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, and (c) an image at a magnification of 2,000 times.

FIG. 17 presents images of the biological tissue rootage face 130(biological tissue rootage face 131) according to the second embodimentof the present invention taken by SEM, including (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

FIG. 18 presents images showing results of an animal experiment,including (a) an X-ray image of an alveolar bone H on a left mandible,(b) an image of a gum S on a right mandible, (c) an X-ray image of thealveolar bone H of the left mandible, and (d) an image of the gum S onthe right mandible.

FIG. 19 presents images of outer surfaces of conventional titaniumfixtures taken by SEM (magnification: 2,000 times), including (a) aproduct manufactured by Company A, (b) a product manufactured by CompanyB, (c) a product manufactured by Company C, and (d) a productmanufactured by Company D.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be explained with reference tothe drawings. Each of sizes and the like in the following explanation isdescribed as an example.

[Dental Implant 1, Fixture 10]

FIG. 1 presents drawings of a dental implant 1 according to the firstembodiment of the present invention, including (a) a screw-type dentalimplant 1A and (b) a cylinder-type dental implant 1B.

The dental implant 1 is a zirconia implant. The dental implant 1includes a screw-type dental implant 1A and a cylinder-type dentalimplant 1B.

The dental implant 1 comprises a fixture 10 fixed to an alveolar bone H(biological tissue, hard tissue), and an abutment 20 fitted into thefixture 10.

A crown 6 called an artificial crown is attached to the abutment 20. Anend side of the abutment 20 opposite to the crown 6 is covered with agum S (biological tissue, soft tissue).

A longitudinal direction (direction along the central axis) of thedental implant 1 is referred to as “vertical”. In the verticaldirection, a side of the crown 6 is referred to as a tip side. The tipis also referred to as a first end. In the vertical direction, a side ofthe fixture 10 is referred to as a root end side. The root end is alsoreferred to as a second end.

A direction perpendicular to the vertical direction is referred to as“horizontal”. A direction around the central axis of the dental implant1 is referred to as a circumferential direction.

The fixture (implant) 10 is a shaft-shaped member having a central hole(not illustrated in the figures) and is formed of a ceramic(biocompatible material, biocompatible ceramic material) includingzirconia.

The fixture 10 includes a screw-type fixture 10A having a male screw 15formed on an outer surface 11, and a cylinder-type fixture 10B having nomale screw 15. Between the screw-type fixture 10A and the cylinder-typefixture 10B, there is a difference only in the presence of the malescrew 15.

The screw-type fixture 10A is screwed into a screw hole formed on thealveolar bone H, so that the fixture 10A is fixed to the alveolar boneH.

The cylinder-type fixture 10B is fitted into a circular hole formed onthe alveolar bone H, so that the fixture 10B is fixed to the alveolarbone H.

A central hole is formed at the center of the tip face 13 of the fixture10. The central hole is formed along the vertical direction.

The fixture 10 may have any shape (length, thickness, etc.). The fixture10 may have no central hole.

[Biological Tissue Activation Surface 30]

The fixture 10 has a biological tissue rootage face 30 (biologicaltissue rootage faces 31 to 35). The biological tissue rootage face 30 isformed on the outer surface 11 of the fixture 10.

In the fixture 10A, the outer surface 11 includes the tip face 13, acollar face 12, and a screw face (male screw 15).

In the fixture 10B, the outer surface 11 includes the tip face 13 and anouter peripheral face 14.

The biological tissue rootage face 30 is excellent in bondability withthe alveolar bone H and the conglutination property with the gum S. Thebiological tissue rootage face 30 has numerous microvilli 41 describedlater. The microvilli 41 are crowded. The biological tissue rootage face30 is a face with dense microvilli.

The biological tissue rootage face 30 may have either or both of smallgrooves 43 and large grooves 45 described later in addition to themicrovilli 41.

The fixture 10 is closely bonded to not only the alveolar bone H butalso the mucosal tissues (soft tissues) surrounding the alveolar bone H.The tip face 13 is closely bonded to the gum S. Thus, the fixture 10 isalso important for the conglutination property (affinity) with the softtissue. If the conglutination property of the fixture 10 with the gum Sis low, the gum S has inflammation, resulting in contraction of the gumS and reduction of the alveolar bone H (bone resorption). Thus, theconglutination property between the fixture 10 and the gums S(conglutination property with the soft tissues) should be improved toprevent (block) bacterial invasion.

The biological tissue rootage face 30 improves osseointegration and gumadhesion of the fixture 10 by the microvilli 41, the small grooves 43,and the large grooves 45. The biological tissue rootage face 30 improvesthe rooting ability of the fixture 10 into the biological tissue(bondability with hard tissues, and conglutination property with softtissues) and accelerates the biological tissue fusion.

(Biological Tissue Rootage Face 31)

FIGS. 2 and 3 present images of the biological tissue rootage face 30(biological tissue rootage face 31) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 30 times, (b) an image at a magnification of 200 times,(c) an image at a magnification of 500 times, (d) an image at amagnification of 2,000 times, (e) an image at a magnification of 5,000times, and (f) an image at a magnification of 10,000 times.

The biological tissue rootage face 31 is an example of the biologicaltissue rootage face 30 and is formed on the outer surface 11 of thefixture 10A.

The biological tissue rootage face 31 has numerous microvilli 41 havingfingertip-shaped tips. The numerous microvilli 41 are densely arranged.The fingertip shape means a shape with a rounded tip (hemisphericalshape) like a fingertip. The tip of the microvillus 41 is ahemispherical protrusion but is not pointed.

The microvillus 41 has a tip outer diameter (diameter) in the order ofnanometers. The nanometer size is also referred to as “nanometer order”,“nanometer scale”, or “nanometer class” in some cases. The term “orderof magnitude” in English is translated as “grade”, “class”, “scale”,“digit” or the like in Japanese.

The tip diameter of the microvillus 41 is 1 nm or more and less than1000 nm. The tip diameter of the microvillus 41 is e.g. 50 nm or moreand less than 500 nm, and may also be e.g. 100 nm or more and less than300 nm.

Also the biological tissue rootage face 31 has a three-dimensionalsurface roughness Sa in the order of nanometers (1 nm or more and lessthan 1000 nm) (arithmetic average height: ISO 25178). For example, thebiological tissue rootage face 31 has a three-dimensional roughness Saof 500 nm or more and less than 800 nm.

The biological tissue rootage face 31 has an interface developed arearatio Sdr (ISO 25178) of 0.1 or more and 2.0 or less. The biologicaltissue rootage face 31 has the interface developed area ratio Sdr ofe.g. 0.5 or more and 1.0 or less.

The biological tissue rootage face 31 has a plurality of large grooves45. The plurality of large grooves 45 are arranged so as to intersectwith each other. The plurality of large grooves 45 are arranged in alattice pattern. This is because egg-shaped osteoblasts of about 20 to30 μm in size are securely fixed inside the large grooves 45.

The large grooves (second grooves) 57 have widths of 10 μm or more and500 μm or less. The widths of the large grooves 45 are e.g. 20 μm ormore and 100 μm or less, and may also be 30 μm or more and 50 μm orless. This is because the osteoblasts are prevented from spreading toomuch.

Depths of the large grooves 45 are 5 μm or more and 500 μm or less, andmay also be e.g. 10 μm or more and 100 μm or less. This is because theosteoblasts are prevented from getting over the large grooves 45.

The large grooves 45 juxtaposed in a lengthwise direction and the largegrooves 45 juxtaposed in a lateral direction (circumferential direction)intersect with each other. An intersection angle of the large grooves 45may be any angle of 60° or larger.

(Biological Tissue Rootage Face 32)

FIGS. 4 and 5 present images of a biological tissue rootage face 30(biological tissue rootage face 32) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, (c) an image at a magnification of 2,000 times, (d) an image at amagnification of 5,000 times, (e) an image at a magnification of 10,000times, and (f) an image at a magnification of 20,000 times.

The biological tissue rootage face 32 is an example of the biologicaltissue rootage face 30 and is formed on the outer surface 11 of thefixture 10B.

The biological tissue rootage face 32 is formed in the same manner asfor the biological tissue rootage face 31.

(Reference: Small Intestinal Villus and Microvillus)

FIG. 6 presents referential images of a small intestinal surface takenby SEM, including (a) an image at a magnification of about 100 times,(b) an image at a magnification of about 5,000 times, and (c) an imageat a magnification of about 10,000 times.

As shown in FIG. 6 (a), the small intestinal inner surface has numerousvilli (villus). The villus refers to fine protrusions protruding from asurface of an organ, and exist in small intestine, placenta and thelike.

As shown in FIGS. 6 (b) and 6 (c), in the surfaces of the villi, evenmore microvilli (microvillus) are densely present. The microvillusitself may also be referred to as soft hair or soft protrusion in somecases.

The tips of the villus and the microvillus are fingertip-shapedprotrusions. The tip diameter of the microvillus is less than 1 μm. Inthe small intestine, placenta, or the like, the surface area issignificantly increased by villi and microvilli, and absorption andbonding are efficiently and effectively performed.

The biological tissue rootage faces 31 and 32 have a structure similarto that of the inner surface of the small intestine or the like. Thelarge grooves 45 are similar to the villi of the biological tissue, andthe microvilli 41 are similar to the microvilli of the biologicaltissue.

For this reason, the biological tissue rootage face 31 has highbondability and conglutination property with the biological tissue (hardtissues such as bone, soft tissues such as mucosal tissue). Thebiological tissue rootage face 31 is considered to have an almost idealshape as a surface configured to be closely bonded to biological tissuesand root thereinto.

(Biological Tissue Rootage Face 33)

FIG. 7 presents images of a biological tissue rootage face 30(biological tissue rootage face 33) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 2,000times, (c) an image at a magnification of 5,000 times, and (d) an imageat a magnification of 10,000 times.

The biological tissue rootage face 33 is an example of the biologicaltissue rootage face 30 and is formed on the outer surface 11 of thefixture 10B.

Like the biological tissue rootage faces 31 and 32, the biologicaltissue rootage face 33 has numerous microvilli 41. The biological tissuerootage face 33 has the same three-dimensional roughness Sa andinterface developed area ratio Sdr as those of the biological tissuerootage faces 31 and 32.

The biological tissue rootage face 33 has a plurality of large grooves45 arranged in parallel. The shape and the like of the large groove 45are as described above.

(Biological Tissue Rootage Face 34)

FIG. 8 presents images of a biological tissue rootage face 30(biological tissue rootage face 34) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, and (c) an image at a magnification of 10,000 times.

The biological tissue rootage face 34 is an example of the biologicaltissue rootage face 30 and is formed on the outer surface 11 of thefixture 10B.

Like the biological tissue rootage faces 31 to 33, the biological tissuerootage face 34 has numerous microvilli 41. The biological tissuerootage face 34 has the same three-dimensional roughness Sa andinterface developed area ratio Sdr as those of the biological tissuerootage faces 31 to 33.

The biological tissue rootage face 34 has the plurality of small grooves43 and large grooves 45. The plurality of small grooves 43 are arrangedin parallel. The plurality of large grooves 45 are also arranged inparallel. The small grooves 43 and the large grooves 45 intersect eachother in a lattice pattern. An intersection angle of the small grooves43 and large grooves 45 may be any angle of 60° or larger.

The shape and the like of the large groove 45 are as described above.

The small grooves (first grooves) 43 have widths of 1 μm or more and 50μm or less and are arranged in parallel. For example, the widths of thesmall grooves 43 are 1 μm or more and 20 μm or less, and may be e.g. 5μm or more and 10 μm or less. Depths of the small grooves 43 are 1 μm ormore and 20 μm or less, and may be e.g. 2 μm or more and 5 μm or less.This is because a mechanical stimulation (mechanical stress) is appliedto osteoblasts.

(Biological Tissue Rootage Face 35)

FIG. 9 presents images of a biological tissue rootage face 30(biological tissue rootage face 35) according to the first embodiment ofthe present invention taken by SEM, including (a) an image at amagnification of 500 times, and (b) an image at a magnification of10,000 times.

The biological tissue rootage face 35 is an example of the biologicaltissue rootage face 30 and is formed on the outer surface 11 of thefixture 10A.

Like the biological tissue rootage faces 31 to 34, the biological tissuerootage face 35 has numerous microvilli 41. The biological tissuerootage face 35 has the same three-dimensional roughness Sa andinterface developed area ratio Sdr as those of the biological tissuerootage faces 31 to 34.

The biological tissue rootage face 35 has the plurality of small grooves43 arranged in parallel and the plurality of large grooves 45 arrangedin parallel. The small grooves 43 and the large grooves 45 are arrangedin parallel. The plurality of small grooves 43 are arranged (superposed)inside the large grooves 45. The small grooves 43 and the large grooves45 are parallel to each other. An intersection angle of the smallgrooves 43 and large grooves 45 may be any angle of 30° or smaller.

The shapes and the like of the small grooves 43 and the large grooves 45are as described above.

FIG. 19 presents referential images of outer surfaces of conventionaltitanium fixtures taken by SEM (magnification: 2,000 times), including(a) a product manufactured by Company A, (b) a product manufactured byCompany B, (c) a product manufactured by Company C, and (d) a productmanufactured by Company D.

As shown in FIG. 19, the outer surface of the conventional fixture isroughened (porosified). These outer surfaces are roughened by etchingtreatment with hydrochloric acid or the like, or blasting treatment.These outer surfaces have numerous pores and furthermore have numerousprotrusions with pointed tips around the pores. The outer surfaces ofthe conventional fixtures have three-dimensional roughnesses Sa of 2 μmor more.

However, there is no protrusion (microvillus) with a hemispherical(fingertip-shaped) tip on any of the outer surfaces of the conventionalfixtures, and the surfaces cannot be considered as microvillus-densesurfaces.

[Abutment 20]

The abutment (implant) 20 is a shaft-shaped member and is formed of azirconia-containing ceramic.

The abutment 20 has a body section 23 and a tapered shaft section 25.The tapered shaft section 25 is fitted into a central hole of thefixture 10, and the body section 23 is disposed so as to be exposed fromthe tip side of the fixture 10.

The body section 23 is formed in a frustoconical shape or the like, towhich the crown 6 is attached with an adhesive, cement, or the like. Inthe body section 23, the end side of the abutment 20 opposite to thecrown 6 (a region not covered with the crown 6) is called a gingivalmargin 24. The gingival margin 24 is exposed between the fixture 10 andthe crown 6.

The abutment 20 has the biological tissue rootage face 30 (biologicaltissue rootage faces 31 to 35). The biological tissue rootage face 30 isformed on an outer surface 21 of the abutment 20. The biological tissuerootage face 30 is formed on a gingival margin face (gingival margin24).

Like the tip face 13 of the fixture 10, the gingival margin 24 isclosely bonded to the gum S. For this reason, the biological tissuerootage face 30 (biological tissue rootage faces 31 to 35) is providedon the gingival margin 24 to facilitate adhesion of the gum S. Thereby,fusion of the abutment 20 with the gum S becomes firm compared tobefore.

The fixture 10 (10A, 10B) has a biological tissue rootage face 30(biological tissue rootage faces 31 to 35) on the outer surface 11. Thiscan enhance fixation (adhesion) of preosteoblasts and osteoblasts to theouter surface 11.

Since the biological tissue rootage face 30 has numerous microvilli 41,the surface area of the outer surface 11 is increased. The area incontact with blood is significantly increased, and the preosteoblastsand osteoblasts easily enter the outer surface 11. In particular, sincethe tip of the microvillus 41 is not pointed but is fingertip-shaped,the preosteoblasts and osteoblasts can smoothly enter the outer surface11. Thus, the osteoblasts proliferate, resulting in firmosseointegration.

The biological tissue rootage face 30 (biological tissue rootage faces31 to 35) has numerous small grooves 43 and large grooves 45. This canenhance proliferation of the osteoblasts.

Since aspects (number, shape, arrangement) of the small grooves 43 andthe large grooves 45 can be variously set, a mechanical stimulation(mechanical stress) can be effectively applied to the preosteoblasts.Consequently, differentiation into osteoblasts is enhanced, and theduration of osseointegration is shortened.

In particular, the biological tissue rootage face 30 has a plurality ofups and downs with different sizes. The microvilli 41 form ups and downsin the order of nanometers. The small grooves 43 form ups and downs witha size of 1 to 9 micrometers. The large grooves 45 form ups and downswith sizes larger than those of the microvilli 41 and the small grooves43. Thus, the biological tissue rootage face 30 can efficiently andeffectively apply a mechanical stimulation to the preosteoblasts.Consequently, the bond between the fixture 10 and the alveolar bone Hbecomes firm compared to before, and the duration of osseointegration isalso shortened.

Even if the fixture 10B does not have the male screw 15, the fixture 10Bexerts the same action and effect as those of the fixture 10A. Since thebiological tissue rootage face 30 exerts a high osseointegrationperformance, the fixture 10B can sufficiently bond to the alveolar boneH.

The abutment 20 has a biological tissue rootage face 30 (biologicaltissue rootage faces 31 to 35) on the outer surface 21 (gingival margin24). Since the biological tissue rootage face 30 has numerous microvilli41, conglutination property with the gingiva (conglutination propertywith the soft tissues) can be enhanced to prevent (block) bacterialinvasion.

For the dental implant 1 (10A, 10B), the biological tissue rootage face30 is formed on the outer surface 11 of the fixture 10 and the outersurface 21 of the abutment 20 respectively, and therefore thebondability with the human body becomes more firm. The dental implant 1Aand the dental implant 1B exert the same action and effect.

The biological tissue rootage face 30 is formed on regions closelybonding to (rooting into) the biological tissues on the outer surfaces11 and 21. The biological tissue rootage face 30 may be formed on oneregion or plural regions, as long as the regions are closely bonded tothe biological tissues. The biological tissue rootage face 30 may haveany area.

The biological tissue rootage face 30 may be formed on substantially theentire outer surfaces 11 and 21.

The biological tissue rootage face 30 may be formed over the entire faceof regions to be closely bonded to the alveolar bone H (collar face 12,outer peripheral face 14, male screw 15) on the outer surface 11. Thebiological tissue rootage face 30 may be formed over the entire face ofregions to be closely bonded to the gum S (tip face 13) on the outersurface 11.

The biological tissue rootage face 30 may be formed only on the outersurface 11, or only on the outer surface 21.

The biological tissue rootage faces 30 on the collar face 12, the tipface 13, the outer peripheral face 14 and the male screw 15 may havedifferent surface properties (surface roughnesses). This is because thealveolar bone H is bonded to the collar face 12 and the male screw 15,and the gum S is conglutinated to the tip face 13.

The biological tissue rootage face 30 of the gingival margin 24 may beformed so as to have the same surface property (surface roughness) asthat of the biological tissue rootage face 30 of the tip face 13. Thisis because the both biological tissue rootage faces 30 are conglutinatedto the gum S.

The small grooves 43 and the large grooves 45 are formed so as to havesemicircular cross sections. The cross-sectional shapes may be e.g. atriangle (isosceles triangle), a rectangle, or the like.

Each of the small groove 43 and large groove 45 may have a uniform widthin the extending direction, or may have different widths, andfurthermore may have a uniform depth in the extending direction, or mayhave different depths.

Each of the plural small grooves 43 and large grooves 45 may have auniform width, or may have different widths, and furthermore may have auniform depth, or may have different depths.

The numbers of the small grooves 43 and large grooves 45 are arbitrary.The small grooves 43 and large grooves 45 may be formed not only in astraight line but also in a curve line. Preferably, the adjacent smallgrooves 43 and the adjacent large grooves 45 are arranged at an intervalas small as possible.

The extending direction of the small grooves 43 and the large grooves 45forms any angle with respect to the vertical direction of the fixture10.

The biological tissue rootage face 30 (biological tissue rootage faces31 to 35) may be formed on both the outer surfaces 11 and 21. It issufficient that any one or more of the biological tissue activationsurfaces 31 to 35.

For the biological tissue rootage face 30, the numbers, shapes andarrangements of the small grooves 43 and the large grooves 45 can bearbitrarily set. The small grooves 43 and the large grooves 45 may haveshapes other than the shapes for the biological tissue rootage faces 31to 35.

The plurality of large grooves 45 may be arranged in a lattice pattern,on which furthermore the plurality of small grooves 43 may be arrangedin a lattice pattern (the large grooves 45 and the small grooves 43intersect each other and are superposed with each other).

The plurality of large grooves 45 may be arranged in parallel, on whichfurthermore the plurality of small grooves 43 may be arranged in alattice pattern (the large grooves 45 and the small grooves 43 intersecteach other and are superposed with each other).

Only the plurality of small grooves 43 may be arranged in a latticepattern.

The biological tissue rootage face 30 may have only numerous microvilli41 and no small grooves 43 and large grooves 45 (see a biological tissuerootage face 131 of the third embodiment).

[Method for Producing Dental Implant 1, and Method for FormingBiological Tissue Rootage Face 30]

The dental implant 1 (1A, 1B) is formed from a biocompatible ceramicmaterial. The fixture 10 (10A, 10B) and the abutment 20 are formed froma zirconium oxide-containing ceramic material.

The manufacturing process for the fixture 10 (10A, 10B) includes amolding step, a sintering step, and a surface processing step. Thesurface processing step is a step of forming a biological tissue rootageface including a laser nonthermal processing step.

Since the manufacturing process for the abutment 20 is the same as themanufacturing process for the fixture 10, the explanation thereof isomitted.

(Molding Step and Sintering Step)

First, in the molding step, a pellet containing a zirconia powder isinjection-molded to obtain a zirconia compact (ceramic compact).

Next, in the sintering step, the zirconia compact is subjected topresintering and main sintering to obtain a zirconia sintered compact(ceramic sintered compact).

(Surface Processing Step: Laser Nonthermal Processing Step)

Next, in the surface processing step, the outer surface 11 of thezirconia sintered compact is irradiated with a laser beam to form thebiological tissue rootage face 30 (biological tissue rootage faces 31 to35) on the outer surface 11.

For the laser beam, a laser beam of an ultrashort pulse laser is used. Alaser beam of a picosecond laser or a femtosecond laser can be used.

The ultrashort pulse laser is an extremely short pulse laser with apulse width (time width) ranging several picoseconds to severalfemtoseconds. A several-picosecond laser is a laser with a pulse widthof one trillionth of a second. A femtosecond laser is a laser with apulse width of one-quadrillionth of a second.

When the outer surface 11 of the zirconia sintered compact is irradiatedwith a laser beam of a femtosecond laser or the like, the outer surface11 is non-thermally processed (laser nonthermal processing).

The nonthermal processing refers to a process that the sintered compactis irradiated with a laser beam under atmospheric pressure (in aircontaining moisture) to instantaneously melt, evaporate and scatter thesintered compact. Since the melted site is instantaneously evaporated,scattered and removed, thermal influence (thermal damage) to thesurroundings of the processed portion is extremely small. For thenonthermal processing, a pulsed laser with a high laser beam output(peak power or energy density) is used.

The outer surface 11 is non-thermally processed with a laser beam toform the biological tissue rootage face 30 having numerous microvilli41. The morphology such as the number and shape (size) of the microvilli41 can be changed by adjusting the output and the like of the laserbeam.

The small grooves 43 and the large grooves 45 are dug into the outersurface 11 by scanning the surface while emitting the laser beam. Theplurality of small grooves 43 and large grooves 45 are formed bymultiple scannings with the laser beam.

The machining width (light diameter) of the laser beam can be changed byadjusting the output of the laser beam. The widths and the depths of thesmall grooves 43 and large grooves 45 can be changed by adjusting theoutput (machining width) of the laser beam. Also, the widths and thedepths of the small grooves 43 and large grooves 45 can be changeddepending on the number of irradiation on the same portion, the scanningspeed, the laser beam output, and the like.

When the small grooves 43 and the large grooves 45 are individuallyformed, first, the large grooves 45 are arranged, and then the smallgrooves 43 are formed.

When the small grooves 43 are arranged, or the large grooves 45 arearranged, or the small grooves 43 and the large grooves 45 are formed ina lattice pattern, scanning is carried out with a laser beam in twointersecting (orthogonal) directions. At this time, the intersectionangle on the scanning is an intersection angle between the small grooves43, between the large grooves 45, or between the small grooves 43 andthe large grooves 45.

When the outer surface 11 is scraped with a laser beam to form the largegrooves 45 and the small grooves 43, numerous microvilli 41 aresimultaneously formed on the inner surfaces of the large grooves 45 andthe small grooves 43. When the outer surface 11 is non-thermallyprocessed with laser, the microvilli 41, the small grooves 43, and thelarge grooves 45 are formed at the same time to form the biologicaltissue rootage face 30 (biological tissue rootage faces 31 to 35).

In the surface processing step, the laser nonthermal processings on thecollar face 12, the tip face 13, and the male screw 15 may be carriedout with different laser beam outputs. Thereby, the collar face 12, thetip face 13, and the male screw 15 have different surface properties(surface roughnesses) of the biological tissue rootage face 30. This isbecause the alveolar bone H is bonded to the collar face 12 and the malescrew 15, and the gum S is conglutinated to the tip face 13.

The formation of the biological tissue rootage face 30 (biologicaltissue rootage faces 31 to 35) is followed by cleaning, sterilizationand the like.

In this way, the fixture 10 is produced.

The surface processing step (formation of the biological tissue rootageface) is not necessarily carried out after the main sintering of thefixture 10.

The presintering of the zirconia compact may be followed by the surfaceprocessing step of the zirconia sintered compact, and then the mainsintering. Through this main sintering, the zirconia sintered compactcontracts, and also the microvilli 41, the small grooves 43, and thelarge grooves 45 become small. Thus, in consideration of the contractionof the zirconia sintered compact, the biological tissue rootage face 30is formed larger. Thereby, a fixture 10 (biological tissue rootage face30) having the same shape as in the case of formation after the mainsintering can be obtained.

The small grooves 43 and the large grooves 45 are not necessarily formedby the laser nonthermal processing. The small grooves 43 and the largegrooves 45 may be formed on the outer surface 11 during the moldingstep. The small grooves 43 and the large grooves 45 may be formed bythermally processing the outer surface 11 with laser prior to the lasernonthermal processing.

As described above, the biological tissue rootage face 30 (biologicaltissue rootage faces 31 to 35) can be formed on the zirconium fixture 10or the like by the laser nonthermal processing.

[Dental Implant 3 and Fixture 50]

FIG. 10 presents drawings of a dental implant 3 according to the secondembodiment of the present invention, including (a) screw-type dentalimplant 3A and (b) cylinder-type dental implant 3B.

The same symbols are attached to members and the like having the sameshapes as of the members of the first embodiment, and the explanationtherefor is omitted.

The dental implant 3 is a metal (titanium alloy) implant. The dentalimplant 3 includes the screw-type dental implant 3A and thecylinder-type dental implant 3B.

The dental implant 3 has a fixture 50 fixed to the alveolar bone H andan abutment 60 fitted into the fixture 50.

The fixture (implant) 50 is a shaft-shaped member having a central hole(not illustrated in the figures) and is formed of a titanium alloy(biocompatible material, biocompatible metallic material).

The fixture 50 is different from the fixture 10 only in the materials.

The fixture 50 includes a screw-type fixture 50A having a male screw 15formed on an outer surface 51, and a cylinder-type fixture 50B having nomale screw 15. The screw-type fixture 50A is different from thecylinder-type fixture 50B only in the presence of the male screw 15.

[Biological Tissue Rootage Face 70]

The fixture 50 has a biological tissue rootage face 70 (biologicaltissue rootage face 71). The biological tissue rootage face 70 is formedon the outer surface 51 of the fixture 50.

In the fixture 50A, the outer surface 51 includes the tip face 13, thecollar face 12, and the screw face (male screw 15).

In the fixture 50B, the outer surface 51 includes the tip face 13 andthe outer peripheral face 14.

Like the biological tissue rootage face 30, the biological tissuerootage face 70 is excellent in the bondability with the alveolar bone Hand conglutination property with the gum S.

The biological tissue rootage face 70 has numerous microvilli 81described later. The microvilli 81 are crowded. Like the biologicaltissue rootage face 30, the biological tissue rootage face 70 is a facewith dense microvilli.

The biological tissue rootage face 70 may have either or both of smallgrooves 83 and large grooves 85 described later in addition to themicrovilli 81.

The biological tissue rootage face 70 is different from the biologicaltissue rootage face 30 only in the materials. The microvilli 81correspond to the microvilli 41, the small grooves 83 to the smallgrooves 43, and the large grooves 85 to the large grooves 45.

(Biological Tissue Activation Surface 71)

FIGS. 11 and 12 present images of the biological tissue rootage face 70(biological tissue rootage face 71) according to the second embodimentof the present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, (c) an image at a magnification of 2,000 times, (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

The biological tissue rootage face 71 is an example of the biologicaltissue rootage face 70 and has numerous microvilli 81. The shape and thelike of the microvilli 81 are the same as those of the microvilli 41.

The biological tissue rootage face 71 has the same three-dimensionalsurface roughness Sa and interface developed area ratio Sdr as those ofthe biological tissue rootage face 30.

The biological tissue rootage face 71 has the plurality of large grooves85 arranged so as to intersect with each other. The plurality of largegrooves 85 are arranged in a lattice pattern. The number, shape and thelike of the large grooves 85 are the same as those of the large grooves45. The biological tissue rootage face 71 has the same morphology as ofthe biological tissue rootage face 31.

As another example of the biological tissue rootage face 70, a face withthe same morphology as those of the biological tissue rootage faces 32to 35 may be formed. The number, shape and the like of the small grooves83 are the same as those of the small grooves 43.

The biological tissue rootage face 70 may have only numerous microvilli81 and no small grooves 83 and no large grooves 85 (see the biologicaltissue rootage face 131 of the third embodiment).

[Abutment 60]

The abutment (implant) 60 is formed of a titanium alloy.

The abutment 60 has the biological tissue rootage face 70 (biologicaltissue rootage face 71). The biological tissue rootage face 70 is formedon an outer surface 61 of the abutment 60. The biological tissue rootageface 70 is formed on the gingival margin face (gingival margin 24).

The abutment 60 is different from the abutment 20 only in the materials.

The fixture 50 (50A, 50B) and the abutment 60 exert the same action andeffect as those of the fixture 10 (10A, 10B) and the abutment 20.

In particular, the biological tissue rootage face 70 exerts the sameaction and effect as those of the biological tissue rootage face 30. Thebiological tissue rootage face 70 improves the ability of rooting intothe biological tissue (bondability with hard tissues, and conglutinationproperty with soft tissue) to accelerate the biological tissue fusion.

Consequently, the dental implant 3 (3A, 3B) exerts the same action andeffect as those of the dental implant 1 (1A, 1B).

[Method for Producing Dental Implant 3, Method for Forming BiologicalTissue Rootage Face 70]

The dental implant 3 (3A, 3B) is formed from a biocompatible metallicmaterial. The fixture 50 (50A, 50B) and the abutment 60 are formed froma titanium alloy material.

The process for the fixture 50 (50A, 50B) includes a machining step anda surface processing step. The surface processing step is a step offorming the biological tissue rootage face and includes an acid etchingstep and a laser nonthermal processing step.

Since the manufacturing process for the abutment 60 is the same as themanufacturing process for the fixture 50, the explanation is omitted.

(Machining Step)

In the machining step, the titanium alloy material is cut using acombined lathe or the like or plastically processed to form a titaniumworkpiece (metal workpiece).

The outer surface 51 of the titanium workpiece is blasted. This isbecause the efficiency of the subsequent acid etching is improved. Theblasting treatment on the titanium workpiece is arbitrarily carried out.

After the machining, the titanium workpiece is washed with water oralcohol.

(Surface Processing Step: Acid Etching Step)

In the surface processing step, first, the outer surface 51 of thetitanium workpiece is acid-etched.

The titanium workpiece is etched by immersing it in hydrochloric acid.The concentration of the hydrochloric acid is e.g. 1% to 20%, the liquidtemperature is e.g. 30° C. to 80° C., and the immersion time is e.g. 10minutes to 60 minutes. The acid used for the etching may be an acidother than hydrochloric acid. Sulfuric acid, hydrofluoric acid, nitricacid, etc., and mixed acids thereof can be used.

After the acid etching step, the titanium workpiece is ultrasonicallywashed with pure water.

FIGS. 13 and 14 present images of the outer surface 51 of theacid-etched titanium workpiece taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, (c) an image at a magnification of 2,000 times, (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

FIGS. 13 and 14 present images of the outer surface 51 of theacid-etched titanium workpiece taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, (c) an image at a magnification of 2,000 times, (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

The outer surface 51 of the acid-etched titanium workpiece (acid-etchedmetal workpiece) has numerous pores and furthermore has numerousprotrusions having pointed tips around the pores. This outer surface 51is rough (porous), and is the same as the outer surface of theconventional fixture (see FIG. 19).

On this outer surface 51, there is no microvillus 41 yet.

(Surface Processing Step: Laser Nonthermal Processing Step)

Next, the outer surface 51 of the titanium workpiece is irradiated withlaser beam to form a biological tissue rootage face 70 (biologicaltissue rootage face 71) on the outer surface 51.

This laser nonthermal processing step is the same as the lasernonthermal processing step of the biological tissue rootage face 30.

When the outer surface 51 of the acid etched titanium workpiece isirradiated with a laser beam of a femtosecond laser or the like, theouter surface 51 is non-thermally processed (laser nonthermalprocessing). The outer surface 51 is non-thermally processed with alaser beam to form the numerous microvilli 81.

The small grooves 83 and the large grooves 85 are dug into the outersurface 51 by scanning the surface while emitting the laser beam. Whenthe outer surface 51 is non-thermally processed with laser, themicrovilli 81, the small grooves 83, and the large grooves 85 are formedat the same time to form the biological tissue rootage face 70(biological tissue rootage face 71).

The formation of the biological tissue rootage face 70 (biologicaltissue rootage face 71) is followed by cleaning, sterilization and thelike.

In this way, the fixture 50 is produced.

The small grooves 83 and the large grooves 85 are not necessarily formedby the laser nonthermal processing. The small grooves 83 and the largegrooves 85 may be formed on the outer surface 51 in the machining step.The small grooves 83 and the large grooves 85 may be formed by thermallyprocessing the outer surface 51 with laser prior to the laser nonthermalprocessing.

As described above, the biological tissue rootage face 70 (biologicaltissue rootage face 71) can be formed on the titanium alloy fixture 50or the like by the acid etching and the laser nonthermal processing.

[Hip Prosthesis 101, Stem 103]

FIG. 15 presents a drawing of a hip prosthesis 101 according to thethird embodiment of the present invention.

When a hip joint is damaged, the hip prosthesis 101 replaces the hipjoint to restore the function of the hip joint. The hip prosthesis 101is composed of a femoral component 102 implanted in a femur J and anacetabular component 106 implanted in an acetabulum K.

The femoral component 102 comprises a stem 103 and a head 104.

The stem 103 is implanted in the femur J (biological tissue, hardtissue) to support the head 104.

The head 104 is a spherical member playing a role of an epiphysis of thefemur J and is formed of a biocompatible ceramic material such aszirconia.

The acetabular component 106 comprises a cup 107 and a liner 108.

The cup 107 is a bowl-shaped member implanted in an acetabulum K(biological tissue, hard tissue) and is formed of a biocompatibleceramic material such as zirconia or a biocompatible metallic materialsuch as a titanium alloy. The biological tissue rootage faces 30 and 70may be formed on the outer surface of the cup 107.

The liner 108 is a bowl-shaped member fixed inside the cup 107 and isformed of e.g. an ultrahigh molecular weight polyethylene resin. Theliner 108 slidably supports the head 104 and plays a role of anarticular surface.

An extending direction of the femoral component 102 is referred to asthe vertical direction. In the vertical direction, the side of the head104 is referred to as a tip (first end), and the side of the stem 103 isreferred to as a distal end (second end). The width direction of thestem 103 is referred to as a lateral direction. The thickness directionof the stem 103 is referred to as an anteroposterior direction.

The stem (implant) 103 is inserted into a narrowing hole Ja formed inthe femur J and osteointegrated. The stem 103 supports the head 104 andtransmits a load to the femur J.

The stem 103 is formed of a biocompatible resin material (biocompatiblematerial). The stem 103 is formed of a polyetheretherketone resin (PEKK:polyetherketoneketone).

The stem 103 has a body section 111, a leg section 112, and a necksection 113, which are integrally formed of a polyetheretherketoneresin.

The body section 111 is a block-shaped portion extending in the verticaldirection, inserted into the narrowing hole Ja, and osteointegrated.

The body section 111 has a length of about 50 mm in the verticaldirection. The body section 111 has a width gradually narrowing from thetip toward the distal end. The tip side has a width of about 33 mm andthe distal end side has a width of about 15 mm. The body section 111 hasa thickness which is substantially constant from the tip side toward thedistal end side. The tip side has a thickness of about 13 mm and thedistal end side has a thickness of about 11 mm.

The leg section 112 is a substantially square pole-shaped portionextending in the vertical direction and is disposed on the end side ofthe body section 111. The leg section 112 guides the body section 111into the narrowing hole Ja and holds the posture of the implanted stem103.

The leg section 112 has a length of about 90 mm in the verticaldirection. The leg section 112 gradually narrows from the tip toward thedistal end.

The neck section 113 is a substantially cylindrical portion extending inthe vertical direction and is disposed on the tip side of the bodysection 111. The neck section 113 protrudes from the narrowing hole Jaand introduces a load from the acetabulum side.

The neck section 113 has a length of about 22 mm. The neck section 113gradually thickens from the tip toward the distal end. On the tip of theneck section 113, a head-joining section is formed.

[Biological Tissue Rootage Face 130]

The stem 103 has a biological tissue rootage face 130 (biological tissuerootage face 131). The biological tissue rootage face 130 is formed onan outer surface 115 of the sites implanted in the narrowing hole Ja(body section 111, leg section 112) on the outer surface of the stem103. The biological tissue rootage face 130 is also formed on at leastthe outer surface 115 of the body section 111.

Like the biological tissue rootage faces 30 and 70, the biologicaltissue rootage face 130 is excellent in bondability with natural bones(femur J). The biological tissue rootage face 130 has numerousmicrovilli 141 described later. The microvilli 141 are crowded. Like thebiological tissue rootage faces 30 and 70, the biological tissue rootageface 130 is a face with dense microvilli.

The biological tissue rootage face 130 has the microvilli 141 and mayfurther have either or both of small grooves and large grooves.

The biological tissue rootage face 130 is different from the biologicaltissue rootage faces 30 and 70 only in the materials. The microvilli 141corresponds to the microvilli 41 and 81, the small grooves correspond tothe small grooves 43 and 83, and the large grooves correspond to thelarge grooves 45 and 85.

(Biological Tissue Rootage Face 131)

FIGS. 16 and 17 present images of a biological tissue rootage face 130(biological tissue rootage face 131) according to the third embodimentof the present invention taken by SEM, including (a) an image at amagnification of 200 times, (b) an image at a magnification of 500times, (c) an image at a magnification of 2,000 times, (d) an image at amagnification of 5,000 times, and (e) an image at a magnification of10,000 times.

The biological tissue rootage face 131 is an example of the biologicaltissue rootage face 130 and has numerous microvilli 141. The shape andthe like of the microvilli 141 are the same as those of the microvilli41 and 81.

The biological tissue rootage face 131 has the same three-dimensionalsurface roughness Sa and interface developed area ratio Sdr as those ofthe biological tissue rootage faces 30 and 70.

As another example of the biological tissue rootage face 130, a facehaving the same morphology as that of the biological tissue rootagefaces 31 to 35, 71 and the like may be formed. The biological tissuerootage face 130 may have small grooves or large grooves. The smallgrooves and the large grooves correspond to the small grooves 43 and 83,and to the large grooves 45 and 85 respectively. The numbers, shapes andthe like of the small grooves and the large grooves of the biologicaltissue rootage face 130 are the same as those of the small grooves 43and 83 and the large grooves 45 and 85 respectively.

The stem 103 exerts the same action and effect as those of the fixtures10 and 50. The biological tissue rootage face 130 exerts the same actionand effect as those of the biological tissue rootage faces 30 and 70.The biological tissue rootage face 130 improves the ability of rootinginto the biological tissue (bondability with hard tissues) to acceleratethe biological tissue fusion.

Particularly, even if the biological tissue rootage face 130 is composedonly of a resin face, the biological tissue rootage face 130 can exertthe ability of rooting into the biological tissue. For this reason, itis unnecessary to coat the resin face with a metal or a ceramic, or tomix the resin material with a metal or a ceramic.

For the hip prosthesis 101, the biological tissue rootage face 130 isformed on the outer surface 115 of the stem 103, and therefore thebondability with the human body becomes firm.

Consequently, the hip prosthesis 101 exerts the same action and effectas those of the dental implants 1 and 3.

[Method for Producing Hip Prosthesis 101, and Method for FormingBiological Tissue Rootage Face 130]

The hip prosthesis 101 is formed from a biocompatible resin material.The stem 103 is formed from polyetheretherketone resin.

The manufacturing process for the stem 103 includes a molding step and asurface processing step. The surface processing step is a step offorming the biological tissue rootage face, and includes a lasernonthermal processing step.

Since the manufacturing processes of the head 104, the cup 107 and theliner 108 are the same as the conventional method, their explanationwill be omitted.

(Molding Step)

In the molding step, a polyetheretherketone resin pellet isinjection-molded to obtain a polyetheretherketone compact (resincompact).

(Surface Processing Step: Laser Nonthermal Processing Step)

Next, in the surface processing step, the outer surface 115 of thepolyetheretherketone compact is irradiated with a laser beam to form thebiological tissue rootage face 130 (biological tissue rootage face 131)on the outer surface 115.

This laser nonthermal processing step is the same as the lasernonthermal processing steps of the biological tissue rootage faces 30and 70.

When the outer surface 115 of the polyetheretherketone compact isirradiated with a laser beam of a femtosecond laser or the like, theouter surface 115 is non-thermally processed (laser nonthermalprocessing). The outer surface 115 is non-thermally processed with alaser beam to form the biological tissue rootage face 131 having thenumerous microvilli 141.

The small grooves and the large grooves may be formed on the outersurface 115 by scanning the surface while emitting the laser beam. Whenthe outer surface 115 is non-thermally processed with laser, themicrovilli 141, the small grooves and the large grooves are formed atthe same time to form the biological tissue rootage face 130.

The formation of the biological tissue rootage face 130 (biologicaltissue rootage face 131) is followed by cleaning, sterilization and thelike.

In this way, the stem 103 is produced.

The small grooves 83 and the large grooves 85 are not necessarily formedby the laser nonthermal processing. The small grooves 83 and the largegrooves 85 may be formed on the outer surface 51 during the machiningstep. The small grooves 83 and the large grooves 85 may be formed bythermally processing the outer surface 51 with laser prior to the lasernonthermal processing.

The biological tissue rootage face 130 is formed on a region (outersurface 115) closely bonding to (rooting into) the femur J on the outersurface of the stem 103. The biological tissue rootage face 130 may beformed on one region or plural regions, as long as the regions are facescapable of closely bonding to the femur J. The biological tissue rootageface 130 may have any area.

The biological tissue rootage face 130 may be formed on substantiallythe entire outer surface 115.

The biological tissue rootage face 130 may be formed only on the outersurface of the body portion 111 (face excluding the outer surface of theleg section 112) on the outer surface 115.

As described above, the biological tissue rootage face 130 (biologicaltissue rootage face 131) can be formed on the stem 103 made of thepolyetheretherketone resin by the laser nonthermal processing.

The stem 103 may be formed of not only the polyetheretherketone resinbut also a biocompatible a biocompatible ceramic material such aszirconia or a biocompatible metallic material such as a titanium alloy.The biological tissue rootage faces 30 and 70 may be formed on the outersurface 115 of the stem 103.

[Animal Experiment]

FIG. 18 presents images showing results of an animal experiment,including (a) an X-ray image of an alveolar bone H on a left mandible,(b) an image of a gum S on a right mandible, (c) an X-ray image of thealveolar bone H of the left mandible, and (d) an image of the gum S onthe right mandible.

One fixture 10A and one fixture 10B were respectively implanted in theright and left alveolar bones H on the mandible of a dog. Four weeksafter the implantation, a state of the fixture 10 was imaged with aroentgen device or the like.

As a result of the animal experiment, it was confirmed that the gum S(gingiva) did not have inflammation. Also, it was confirmed that the gumS did not contract and the alveolar bone H did not reduce.

The conglutination property of the fixture 10 (10A, 10B) with the gum S(conglutination property to soft tissues) could be improved to prevent(block) bacterial invasion.

The fixture (10A, 10B) was osteointegrated to the extent of notwithdrawing them from the alveolar bone H by human power. Theosseointegration of the fixture (10A, 10B) with the alveolar bone H(bondability with hard tissues) could be improved to shorten theduration of osseointegration.

In this manner, the rooting ability (bondability with hard tissues andconglutination property with soft tissues) of the fixture 10 (10A, 10B)could be improved to enhance (accelerate) the biological tissue fusion.

The present invention is not limited to the above-described embodimentsbut includes the embodiments with various modifications withoutdeparting from the purpose of the present invention. That is, thespecific shapes, configurations and the like cited in the embodimentsare merely examples, and can be appropriately changed.

In the above embodiments, the dental implants 1 and 3 to be implanted inthe alveolar bone H, and the hip prosthesis 101 implanted in the femur Jhave been explained, but the present invention is not limited thereto.

The implant of the present invention may be an artificial bone, a boneprosthetic material, or the like. The artificial bone and the boneprosthetic material are used to compensate for a bone defective site dueto fracture, tumor resection or the like, a cartilage removed by lumbarsurgery, and the like.

The implant according to the present invention may be a member of anartificial joint, an osseointegration material used for fixing afracture site, a fixture for a spine or the like (a spinal implant or alumbar implant).

The implant is not necessarily implanted in a living body (in a body)but may be fixed to a body surface. The implant may be applied not onlyto humans but also pets, livestock, and the like.

The biological tissue rootage face may have ups and downs such as othergrooves and ridges in addition to or instead of the small grooves andthe large grooves.

In the above embodiments, although the case of zirconia (zirconiumoxide) has been described for the biocompatible ceramic material, thematerial may be a combined material of zirconia with carbon, resin,glass or the like. It is sufficient that zirconia (zirconium oxide) iscontained in a volume ratio of at least 50% relative to the implant.Zirconia (zirconium oxide) is contained in a volume ratio of 90% or morerelative to the implant.

As the biocompatible ceramic material, alumina (aluminum oxide), yttriumoxide, hafnium oxide, silicone oxide, magnesium oxide, cerium oxide orthe like may be adopted.

The biocompatible metallic material may be copper, titanium, a titaniumalloy, a cobalt-chromium alloy, or the like. The biocompatible resinmaterial may be silicon, nylon, POM, a composite material or the like.

REFERENCE NUMERALS

-   1, 1A, 1B, 3, 3A, 3B dental implant-   10, 10A, 10B fixture (implant)-   11 outer surface-   12 collar face-   13 tip face-   14 outer peripheral face-   15 male screw (screw face)-   20 abutment (implant)-   21 surface-   24 gingival margin (gingival margin face)-   30 (31, 32, 33, 34) biological tissue rootage face-   41 microvilli-   43 small groove (first groove)-   45 large groove (second groove)-   50, 50A, 50B fixture (implant)-   60 abutment (implant)-   70 (71) biological tissue rootage face-   71 microvilli-   83 small groove (first groove)-   85 large groove (second groove)-   101 hip prosthesis-   103 stem (implant)-   111 body section-   112 leg section-   115 outer surface-   130, 131 biological tissue rootage face-   141 microvilli-   H alveolar bone (biological tissue, hard tissue)-   S gum (biological tissue, soft tissue)-   J femur (biological tissue, hard tissue)-   K acetabulum (biological tissue, hard tissue)

The invention claimed is:
 1. An implant, comprising: a ceramic sinteredcompact composed of a biocompatible ceramic material, and a lasernonthermal processed surface provided on an outer surface of the ceramicsintered compact, wherein the laser nonthermal processed surface isformed by non-thermally processing the outer surface of the ceramicsintered compact with laser and removing portions of the outer surfacethat are melted by the laser, wherein fingertip-shaped microvillielongate from the laser nonthermal processed surface, thefingertip-shaped microvilli being formed by the nonthermal processingwith the laser, and wherein each of the fingertip-shaped microvilli hasa tip diameter of less than 1000 nanometers.
 2. The implant according toclaim 1, wherein the laser nonthermal processed surface has a groovehaving a width of 1 μm or more and 50 μm or less and a depth of 1 μm ormore and 20 μm or less; and wherein the fingertip-shaped microvilli areelongated from an inner surface of the groove.
 3. The implant accordingto claim 1, wherein the laser nonthermal processed surface has a groovehaving a width of 10 μm or more and 500 μm or less and a depth of 5 μmor more and 100 μm or less; and wherein the fingertip-shaped microvilliare elongated from an inner surface of the groove.
 4. The implantaccording to claim 1, wherein the laser nonthermal processed surface hasa large groove having a width of 10 or more and 500 μm or less and adepth of 5 μm or more and 100 μm or less; wherein the laser nonthermalprocessed surface has a small groove arranged on an inner surface of thelarge groove and having a width of 1 μm or more and 50 μm or less and adepth of 1 μm or more and 20 μm or less; and wherein thefingertip-shaped microvilli are elongated from an inner surface of thesmall groove.
 5. The implant according to claim 1, wherein athree-dimensional surface roughness Sa of the laser nonthermal processedsurface is from 500 nm to 800 nm, and wherein an interface developedarea ratio of the laser nonthermal processed surface is from 0.1 to 2.0.6. A method of forming an implant, comprising: forming a ceramicsintered compact composed of a biocompatible ceramic material; andsubjecting an outer surface of the ceramic sintered compact to a lasernonthermal process and removing portions of the outer surface melted bya laser light, so as to form a laser nonthermal processed surface on theouter surface and fingertip-shaped microvilli that elongate from thelaser nonthermal processed surface, wherein fingertip-shaped microvillihas a tip diameter of less than 1000 nanometers.
 7. The method forforming an implant according to claim 6, wherein the laser nonthermalprocessed surface has a groove having a width of 1 μm or more and 50 μmor less and a depth of 1 μm or more and 20 μm or less; and wherein thefingertip-shaped microvilli are elongated from an inner surface of thegroove.
 8. A method for forming an implant according to claim 6, whereinthe laser nonthermal processed surface has a groove having a width of 10μm or more and 500 μm or less and a depth of 5 μm or more and 100 μm orless; and wherein the fingertip-shaped microvilli are elongated from aninner surface of the groove.
 9. A method for forming an implantaccording to claim 6, wherein the laser nonthermal processed surface hasa large groove having a width of 10 μm or more and 500 μm or less and adepth of 5 μm or more and 100 μm or less; wherein the laser nonthermalprocessed surface has a small groove arranged on an inner surface of thelarge groove and having a width of 1 μm or more and 50 μm or less and adepth of 1 μm or more and 20 μm or less; and wherein thefingertip-shaped microvilli are elongated from an inner surface of thesmall groove.